This invention concerns machines for drying, polishing and burnishing cutlery and other metal tableware with the use of a treatment material, such as, for example, a granulation of corn shavings.
In restaurants, canteens, communities and similar, the dirty cutlery, plates, glasses, etc. are cleaned in the dishwasher, then dried with the aid of a drying material and finally heated to completely remove water.
In a previous disclosure of the same applicant, corresponding to U.S. Pat. No. 6,110,020, there was a specific proposal for a machine that dries, polishes and burnishes cutlery and metal tableware, with the purpose of removing all traces of lime-scale, marks or stains from the surface and, thereby, polishing the metal.
Such a machine has a vibrating tank in which there is a channel through which the drying material and the objects to be treated have to pass. The tank with the channel is generally made by welding metal sheets together and covering this with a protective plastic lining. The channel spirals upwards, from an entrance chute at the level of a central mouth for the loading of objects, up to an exit chute on an outer rim of the tank. The drying material and the articles gradually progress up the spiral channel, thanks to the vibration applied to the tank. The channel is substantially quadrilateral in cross-section, with vertical side walls and a flat bottom. Seen in layout, it has a polygonal shape, with straight walls joined by corner pieces, which are also straight.
Said machine, however, is not completely free of drawbacks. In fact, on account of the shape of the treatment channel, the articles being treated come to rest on the flat bottom and have difficulty in advancing regularly up along the channel. These difficulties are added to by the fact that the articles tend to end up crosswise in the channel, becoming blocked against the side walls. This is even more likely in the corner areas at the end of each straight section, where the items have to change direction. This is at the detriment of the machine""s functionality and efficiency, with the further disadvantage of making the machine very noisy, as the pieces bump against the channel walls.
The present invention has been designed effectively to remove the drawbacks of the machine described above.
In fact, one of the objects of this invention is to make and supply a machine for drying, polishing and burnishing metal tableware with an improved shape, operation and inclination of the channel that the drying material and articles have to climb, improving the efficiency and reliability of the machine and the effectiveness of the treatment.
Said object and the advantages it involves is reached, in accordance with the present invention, with a machine for drying, polishing and burnishing cutlery and metal articles, in which the treatment channel, climbing in a spiral shape from an entrance chute to an exit chute, has, in a transverse cross-section, a U-shaped bottom defined by a surface that is substantially a concave cylinder, and, lengthways, has an alternating series of straight sections and curved joints.
Thus, the channel is freed of sharp bends and corners that may block the advance of the articles during the treatment phase. Thanks to the concave bottom, furthermore, the articles tend to remain and return to the lowest part of said bottom, at the centre of the channel, immersed in the drying material, without ever ending up crossways, bumping against the walls and becoming stuck, even when following the curves that mark a change in direction. Consequently, the machine is less noisy, even though it has no plastic protective lining along the channel surfaces.
Another benefit lies in the fact that the treatment channel has a variable inclination, with a steeper gradient towards the exit passage or chute. This means that the drying material and the articles advance more slowly, at least in the final part of the channel, in order to improve the effectiveness of the treatment and to favour the separation of the drying material from the articles when they reach a grill at the end.